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PubMed1988

[UV-spectrophotometry in drug control. 41. Drug substances with chromophores and auxochromes in monocyclic compounds (pyrazolone, pyrazolidine, pyridazine, pyrimidine and pyrazine) and bicyclic compounds (benzoxazole, imidazole, benzthiazole and indene)].

The results of a systematic examination of the spectra of 15 drug substances with chromophores and auxochromes in monocyclic (pyrazolone, pyrazolidin, pyridazine, pyrimidine and pyrazine) and bicyclic compounds (benzoxazol, imidazole, benzthiazole and indene) in the UV and visible range were evaluated. Influences of substituents and solvents on shifts of the E, K, B and R bands were discussed.

Benzothiazoles↗
PubMedDate not supplied

Studies on pyrazine derivatives. Part XIII. synthesis and tuberculostatic activity of some 6-alkyl-amino- and 6-dialkylhydrazinopyrazine-2-carboxylic acids derivatives.

6-RNH- and 6-R2NNH-pyrazine-2-carbothioamides 1--3, 5, 6, 9 and 14 were obtained from 2-cyano-6-chloropyrazine. In the in vitro screening the thioamides were active against Myc. tuber. H37Rv at the conc. range of 15.6--250 microgram/cm3. The most active thioamides 1 and 8, however, do not act in experimental tuberculosis in guinea pigs.

Amines↗
PubMedDate not supplied

Studies on the quantitative structure-activity relationships in pyrazine carbothioamide derivatives.

Quantitative relationships were studied between tuberculostatic potency in vitro and structure parameters of pyrazine carbothioamides. The activity of the compounds was found to be dependent on the parameters related both to the size of the substituent and electronic properties of the molecule. An equation was obtained, statistically significant on the 99% level, which described about 71% of variance of activity data for the compounds under study as a function of molar refractivity of the substituent and the wave length at which absorption maximum occured.

Amides↗
PubMed1987

Homology between the pyrazine-binding protein from nasal mucosa and major urinary proteins.

Sequence analysis of the pyrazine-binding protein from bovine olfactory mucosa reveals marked homology with a family of proteins of unknown function found in the urine of the adult male mouse and rat. In view of the dramatic biological responses to odorants transmitted in male rodent urines, it is proposed that these proteins play important roles in some aspects of odor transmission and reception.

Amino Acid Sequence↗
PubMed1989

Complete amino acid sequence of pyrazine-binding protein from cow nasal mucosa.

The sequence is reported of the pyrazine-binding protein from cow olfactory/respiratory mucosa. The protein consists of 159 amino acids and clearly belongs to the retinol-binding protein family. It is most closely related to the urinary proteins from mice and rats and to the odour-binding protein from rat nasal epithelium. It is unique however, in that only one of the otherwise conserved features of the family is still present--namely a single tryptophan. Most surprisingly the protein contains no cysteine and, therefore, does not rely for its structural stability on the disulphide bond(s) present in other members of this group. A model for the protein has been constructed based on the co-ordinates of beta-lactoglobulin. From this, it is possible to identify residues which may line the binding site. The impression gained is of a much larger pocket than occurs with retinol-binding protein or beta-lactoglobulin. The character of the binding pocket remains essentially hydrophobic but with a significant reduction in its aromatic content and an increase in H-bonding side chains.

Amino Acid Sequence↗
PubMed1990

Computer-automated structure evaluation of gastric antiulcer compounds: study of cytoprotective and antisecretory imidazo[1,2-a]pyridines and -pyrazines.

A quantitative structure-activity relationship study of a set of antiulcer compounds has been performed using the computer-automated structure evaluation methodology. Computer-automated structure evaluation identified cyanomethyl and hydroxymethyl functionalities, substituted in the 3-position of imidazo[1,2-a]pyridine and -Pyrazine, as descriptors relevant to antisecretory activity. The phenoxy group at the 8-position and the methyl group at the 2-position were shown to be sterically involved in the activity. A parabolic relationship was observed between the antisecretory activity and the logarithm of the partition coefficient of the compounds. Thus, hydrophobicity is found to be a necessary criterion for the inhibition of acid secretion. An attempt has been made to provide a rationale for designing a more potent antiulcer agent in this series of congeneric compounds.

Animals↗
PubMedDate not supplied

Measurement of rate constants for quenching singlet oxygen with a Cypridina luciferin analog (2-methyl-6-[p-methoxyphenyl]-3,7-dihydroimidazo [1,2-a]pyrazin-3-one) and sodium azide.

The rate constants for [1O2] [MCLA] and [1O2] [NaN3] were measured by quenching the near-infrared emission (1 delta g----3 sigma g) in steady state with MCLA and NaN3, respectively. 1O2 was constantly generated by energy transfer to O2 from Ar laser-excited Rose Bengal. The Stern-Volmer plots yielded the second-order rate constants of 2.94 x 10(9) M-1 S-1 and 3.83 x 10(8) M-1 S-1 for quenching 1O2 with MCLA and NaN3 in water at pH 5.4, respectively. The 1O2 + MCLA reaction emitted light with maximum at 465 nm at pD 4.5 identical to the O(2-) + MCLA reaction.

Azides↗
PubMed1977

Anorexigenic and ancillary actions of MK-212 (6-chloro-2-(1-piperazinyl)-pyrazine; CPP).

In rats allowed to eat for 2 h/day and injected i.p. 30 min before feeding, MK-212, ED50 = 1.5 mg/kg, was two times more potent as an anorexigen than fenfluramine. However, the compounds were equiactive in the rat following p.o. administration 1.5 or 3 h before the test, while fenfluramine was more potent if the interval was extended to 6 h. In cats permitted to eat for 3 h/day, the ED50 dose (mg/kg p.o.) for MK-212 determined at 0.5, 1 and 3 h after feeding was, respectively, 15, 10, and 3 times less than that of fenfluramine. Emesis and diarrhea were frequently observed ancillary effects in cats treated with fenfluramine, whereas apparent sedation and salivation were commonly detected in animals after MK-212. In rats or cats pretreated with methergoline, the decrease in food consumption elicited by MK-212 was markedly inhibited, suggesting that the mechanism of action involves a serotoninlike effect. Compared with the marked stimulant action of amphetamine, MK-212 had only a minor and inconsistent effect on motor activity in rats and mice. Similar results were obtained with fenfluramine. MK-212 was not self-administered by rats, while the self-administration of amphetamine and morphine were demonstrated using the same experimental protocol.

Animals↗
PubMed1977

Central serotonin-like activity of 6-chloro-2-[1-piperazinyl]-pyrazine (CPP; MK-212).

CPP, administered systemically, elicited four distinct responses characteristic of serotonin-receptor activation in the central nervous system. The crossed extensor reflex in the acutely spinalized rat was enhanced by treatment with CPP, 1-16 mg/kg. CPP, 1.11-10 mg/kg, elicited a dose-related increase in head twitches in mice. A complex motor syndrome in rats similar to that produced by pargyline plus tryptophan (or other treatments effecting increased activation of central serotonin receptors) was produced by 1.25-5 mg/kg of CPP. An increase in twitch frequency of the mylohyoideus muscle in the urethane anesthetized rat occured after CPP at 0.1 mg/kg or less. Complete abolition of all four effects of CPP was achieved by pretreatment with the centrally acting indoleamine antagonist methergoline. The peripherally acting serotonin antagonist xylamidine was ineffective or only weakly active, depending upon the test procedure, in preventing the serotonin-like actions of CPP. These findings indicate that CPP has a serotoninmimetic action in the central nervous system.

Animals↗
PubMed1986

A chemiluminescent probe with a Cypridina luciferin analog, 2-methyl-6-phenyl-3,7-dihydroimidazo[1,2-a]pyrazin-3-one, specific and sensitive for O2- production in phagocytizing macrophages.

When a Cypridina luciferin analog (the title compound) was added to a macrophage suspension in Hank's balanced salt solution (control), the system emitted a weak, but detectable light, which was not altered in the presence of superoxide dismutase. The same system, however, emitted a much stronger light, just after the addition of a trigger, opsonized zymosan. The luminescence was suppressed to the control level in the presence of superoxide dismutase, while it was only slightly influenced, if at all, by NaN3, a scavenger of singlet oxygen and an inhibitor of myeloperoxidase. Some other results obtained also indicate the participation of O2- in the luciferin analog-dependent luminescence in macrophages during phagocytosis.

Animals↗
PubMed1986

Gas chromatographic assay for the new antitumor agent pyrazine-2-diazohydroxide (diazohydroxide) and its stability in buffer, blood and plasma.

Diazohydroxide is a new antitumor agent being considered for clinical trial. A sensitive and specific assay for diazohydroxide in physiological media, plasma and blood has been developed based on conversion of diazohydroxide to 2-chloropyrazine in the presence of strong hydrochloric acid. The 2-chloropyrazine is extracted into the ethyl acetate and separated by capillary gas chromatography with nitrogen-phosphorus detection. Using 0.2 ml plasma the assay was linear up to 100 micrograms/ml diazohydroxide and had a lower limit of detectability for diazohydroxide of 50 ng/ml. The coefficient of variation of the assay at 1 micrograms/ml was 6.7%. Breakdown of diazohydroxide was rapid under mild acid conditions but slower under alkaline conditions,. The half-life of diazohydroxide in 0.1 M sodium phosphate buffer, pH 6.0, at room temperature was 5 min and at pH 8.0, 480 min. Breakdown of diazohydroxide in plasma was biphasic. In fresh mouse plasma diazohydroxide had a terminal half-life at 37 degrees C of 72 min while in fresh human plasma the terminal half-life was 23 min and in fresh blood 21 min. Diazohydroxide accumulated in red blood cells at 37 degrees C to a concentration 68% above the concentration in plasma. Diazohydroxide was 49% bound to human plasma proteins at room temperature.

Animals↗